Tips

• Make sure you treat latitude and longitude columns correctly when building spatial data from raw Lat/Long coordinate pairs
• Make sure to double-check your projection Coordinate Reference System (CRS) and make sure that that projection CRS is appropriate for your data
• Most spatial operations require the spatial data are in the same CRS, make sure you double check the CRS before you conduct spatial operations such as overlay, spatial join, and distance query
• Make sure you know what is the unit measure of your projection. See here for more information about projection
• Think about what the results will look like beforehand. If the results are different from what you have expected, then you know there are something wrong either in you mind or in the program
• Most importantly, backup your scripts and data frequently or use version control